The plots of the estimated Rt over the most recent weeks show the Rt following a declining trend from peaks of around 1.50 to values just below 1. This downward trend in Rt from the peak is still largely driven by the indices of mobility, and particularly by the recent school holiday.
The incidence of deaths, which has been falling since the end of March, has increased again over the past six weeks and continues to rise, although the actual numbers remain low in comparison to the two previous waves of infection. Our projections for the number of deaths are close to a peak by the end of the three-week period.
Plots of the IFR over time show that from the end of January we estimate a decreasing IFR in all adult age groups, but most steeply in the older ages. This drop indicates the benefits of immunisation against death over and above the benefits against infection. Specifically, there is an estimated fall to a still-high 2.5% (2.3%–2.8%) in the over-75s and 0.15% (0.14%–0.16%) overall. The overall impact of the immunisation programme can be seen more clearly in the ‘All Ages’ plot, where the precipitous decline in IFR since late January is a product of this efficacy against death but also of the increasing proportion of infections in young people; older age groups are immunised and become more protected against infection. The impact of the immunisation in the 25–44 age-group is beginning to become apparent with a fall after an initial plateau.
For context, alongside the data used here, reported new positive tests have suggested a declining epidemic over the last couple of weeks. This trend is highly dependent on the propensity to test and, therefore, difficult to interpret. However, an initial downturn has also started to appear in hospital admissions in some regions. Prevalence of infection, as estimated by the ONS Coronavirus Infections Survey, remains high at close to 1.60% in England, but the rate of increase is slowing down.
Real-time tracking of an epidemic, as data accumulate over time, is an essential component of a public health response to a new outbreak. A team of statistical modellers at the MRC Biostatistics Unit (BSU), University of Cambridge, are working to provide regular now-casts and forecasts of COVID-19 infections and deaths. This information feeds directly to the SAGE sub-group, Scientific Pandemic Influenza sub-group on Modelling (SPI-M), and to regional Public Health England (PHE) teams.
We fit a transmission model (Birrell et al. 2020) to a number of data sources (see ‘Data Sources’), to reconstruct the number of new COVID-19 infections over time in different age groups and NHS regions, estimate a measure of ongoing transmission and predict the number of new COVID-19 deaths.
We use:
Data are stratified into eight age groups: <1, 1-4, 5-14, 15-24, 25-44, 45-64, 65-74, 75+, and the NHS England regions (North East and Yorkshire, North West, Midlands, East of England, London, South East, South West).
Value of \(R_t\), the average number of secondary infections due to a typical infection today.
The percentage of a given group that has been infected.
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | -0.01 | -0.02 | 0.00 |
| East of England | -0.01 | -0.04 | 0.01 |
| East Midlands | -0.01 | -0.03 | 0.02 |
| London | -0.01 | -0.04 | 0.01 |
| North East | -0.03 | -0.05 | -0.01 |
| North West | -0.04 | -0.08 | -0.01 |
| South East | 0.00 | -0.02 | 0.02 |
| South West | -0.02 | -0.05 | 0.00 |
| West Midlands | -0.01 | -0.03 | 0.01 |
| Yorkshire and The Humber | -0.01 | -0.03 | 0.01 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 74.76 | 37.17 | 1007.21 |
| East of England | 76.88 | 17.61 | NA |
| East Midlands | 96.63 | 24.01 | NA |
| London | 48.86 | 18.36 | NA |
| North East | 21.25 | 12.46 | 68.03 |
| North West | 15.43 | 8.72 | 47.61 |
| South East | NA | 31.78 | NA |
| South West | 30.07 | 13.08 | NA |
| West Midlands | 115.57 | 22.92 | NA |
| Yorkshire and The Humber | 75.28 | 21.60 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | NA | NA |
| East of England | NA | 47.50 | NA |
| East Midlands | NA | 43.21 | NA |
| London | NA | 132.63 | NA |
| North East | NA | NA | NA |
| North West | NA | NA | NA |
| South East | 552.08 | 30.79 | NA |
| South West | NA | 324.27 | NA |
| West Midlands | NA | 53.64 | NA |
| Yorkshire and The Humber | NA | 52.63 | NA |
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 0.02 | 0.02 | 0.03 |
| East of England | 0.02 | 0.00 | 0.05 |
| East Midlands | 0.03 | 0.01 | 0.05 |
| London | 0.02 | 0.01 | 0.04 |
| North East | 0.01 | 0.00 | 0.03 |
| North West | -0.01 | -0.02 | 0.01 |
| South East | 0.04 | 0.02 | 0.06 |
| South West | 0.02 | 0.00 | 0.04 |
| West Midlands | 0.03 | 0.01 | 0.05 |
| Yorkshire and The Humber | 0.03 | 0.01 | 0.05 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | NA | NA |
| East of England | NA | NA | NA |
| East Midlands | NA | NA | NA |
| London | NA | NA | NA |
| North East | NA | 192.99 | NA |
| North West | 101.96 | 29.57 | NA |
| South East | NA | NA | NA |
| South West | NA | 172.75 | NA |
| West Midlands | NA | NA | NA |
| Yorkshire and The Humber | NA | NA | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 28.72 | 22.29 | 39.95 |
| East of England | 28.30 | 14.61 | 188.91 |
| East Midlands | 24.22 | 13.61 | 74.08 |
| London | 29.91 | 17.13 | 92.55 |
| North East | 52.66 | 21.20 | NA |
| North West | NA | 50.82 | NA |
| South East | 18.59 | 12.00 | 35.92 |
| South West | 41.85 | 17.03 | NA |
| West Midlands | 22.35 | 13.60 | 50.94 |
| Yorkshire and The Humber | 25.40 | 14.80 | 76.49 |
The shaded areas show periods of national lockdown, the green lines the dates (once confirmed) of the steps in the roadmap in the UK Governement’s COVID-19 Response – Spring 2021, and the red line shows the date these results were produced (30 Jul).
The figure below shows the probability that \(R_t\) is greater than 1 (ie: the number of infections is growing) in each region over time. Clicking the regions in the legend allows lines to be added or removed from the figure.
Copyright © MRC Biostatistics Unit, University of Cambridge